标题: 一道语法题 [打印本页] 作者: 憧憬 时间: 2004-1-8 12:10 标题: 一道语法题 求助一道语法题 有一道语法题的答案是：Because natural gas is composed mostly of methane, a simple hydrocarbon, vehicles powered by natural gas emit less of certain pollutants than those burning gasoline or diesel fuel.请问为什么要在比较结构中省略助动词do.白勇说比较结构中be动词可省可不省，但是助动词不能省，为什么答案不是than those burning gasoline or diesel fuel do 呢
2004-1-5 0:41:00 “700分的承诺，马仕德2004GMAT冲刺班”
作者: Snazzy 时间: 2004-1-8 12:26
1, most ot the times, "do" should not be omitted. but i did see a couple of times where it is omitted. 2, In GMAT, if "do" is not omitted, it tends to be placed in a reverse , eg. ... than do vehicles ...作者: 海海 时间: 2004-1-8 12:41
同意Snazzy的看法, 我在这个问题上也困惑过. 看过Snazzy的语法讲解, 感觉你在SC上的造诣已经属于上乘. 可以留个MSN吗, 我的是yuhai1234(A) hotmail.com. 希望能和你多讨论.